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    "# File: five-twist.ipynb\n",
    "# Code: Claude Code and Codex\n",
    "# Review: Ryoichi Ando (ryoichi.ando@zozo.com)\n",
    "# License: Apache v2.0"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "2eb84f3d-b318-4313-9004-d661aa55d39a",
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   "source": [
    "import numpy as np\n",
    "from frontend import App\n",
    "\n",
    "# create an app\n",
    "app = App.create(\"five-twist\")\n",
    "\n",
    "# create a cylinder mesh with specified radius and length\n",
    "half_length = 2.6\n",
    "V, F = app.mesh.cylinder(r=0.55, min_x=-half_length, max_x=half_length, n=180)\n",
    "app.asset.add.tri(\"cylinder\", V, F)\n",
    "\n",
    "# create a scene\n",
    "scene = app.scene.create()\n",
    "objs = []\n",
    "\n",
    "# arrange 5 cylinders in a circular pattern\n",
    "n, r = 5, 1\n",
    "for i in range(5):\n",
    "    t = 2 * i / n * np.pi\n",
    "    x, y = r * np.cos(t), r * np.sin(t)\n",
    "    objs.append(scene.add(\"cylinder\").at(0, x, y).jitter())\n",
    "\n",
    "# configure material properties and animations for each cylinder\n",
    "for obj in objs:\n",
    "\n",
    "    # set bending stiffness, contact gap, Young's modulus, Poisson's ratio and density\n",
    "    (\n",
    "        obj.param.set(\"bend\", 500.0)\n",
    "        .set(\"contact-gap\", 4e-3)\n",
    "        .set(\"young-mod\", 1e4)\n",
    "        .set(\"poiss-rat\", 0.25)\n",
    "        .set(\"density\", 3.5)\n",
    "    )\n",
    "\n",
    "    # define animation parameters for twisting motion\n",
    "    angular_vel, move_delta, scale, t_end, t_wait = 360, 1, 0.75, 25, 5\n",
    "    x, y, z = obj.position\n",
    "\n",
    "    # pin and animate left end - spin, scale and move\n",
    "    left_pin = obj.pin(obj.grab([-1, 0, 0]))\n",
    "    left_pin.spin(axis=[1, 0, 0], angular_velocity=angular_vel, t_end=t_wait).move_by(\n",
    "        [move_delta, 0, 0], 0.0, t_end\n",
    "    )\n",
    "    left_pin.scale(scale, 0.0, t_wait, center=[-x-half_length, -y, -z])\n",
    "\n",
    "    # pin and animate right end - spin in opposite direction, scale and move\n",
    "    right_pin = obj.pin(obj.grab([1, 0, 0]))\n",
    "    right_pin.spin(axis=[-1, 0, 0], angular_velocity=angular_vel, t_end=t_wait).move_by(\n",
    "        [-move_delta, 0, 0], 0.0, t_end\n",
    "    )\n",
    "    right_pin.scale(scale, 0.0, t_wait, center=[-x+half_length, -y, -z])\n",
    "\n",
    "    # add additional spinning motion\n",
    "    angular_vel, t_end = 180, 15\n",
    "\n",
    "    left_pin.spin(\n",
    "        center=[-x, -y, -z],\n",
    "        axis=[1, 0, 0],\n",
    "        angular_velocity=angular_vel,\n",
    "        t_start=t_wait,\n",
    "        t_end=t_end,\n",
    "    )\n",
    "\n",
    "    right_pin.spin(\n",
    "        center=[-x, -y, -z],\n",
    "        axis=[-1, 0, 0],\n",
    "        angular_velocity=angular_vel,\n",
    "        t_start=t_wait,\n",
    "        t_end=t_end,\n",
    "    )\n",
    "\n",
    "# compile the scene and report stats\n",
    "scene = scene.build().report()\n",
    "\n",
    "# preview the initial scene\n",
    "scene.preview()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "70ce60bb-552f-4d59-9116-1cdc805cbe5f",
   "metadata": {},
   "outputs": [],
   "source": [
    "# create a new session with the compiled scene\n",
    "session = app.session.create(scene)\n",
    "\n",
    "# set session parameters - timestep, frames, disable gravity\n",
    "(\n",
    "    session.param.set(\"dt\", 1 / 60)\n",
    "    .set(\"frames\", 480)\n",
    "    .set(\"gravity\", 0.0)\n",
    ")\n",
    "\n",
    "# build this session\n",
    "session = session.build()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "ab76b71d-6c12-486b-9ff0-f8713f96f0a7",
   "metadata": {},
   "outputs": [],
   "source": [
    "# start the simulation and live-preview the results\n",
    "session.start().preview()\n",
    "\n",
    "# also show simulation logs in realtime\n",
    "session.stream()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "6f295e70-36ec-4771-9458-f29adc6a1ded",
   "metadata": {},
   "outputs": [],
   "source": [
    "# create an animation from the simulation results\n",
    "session.animate()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "6824e966-cc2d-4001-9c7f-1a56bc242284",
   "metadata": {},
   "outputs": [],
   "source": [
    "# export the animation to file\n",
    "session.export.animation()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "2f830039-41b5-4cb7-9bc5-059542d53edc",
   "metadata": {},
   "outputs": [],
   "source": [
    "# this is for CI\n",
    "if app.ci:\n",
    "    assert session.finished()"
   ]
  }
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